KR930008185B1 - Chrominance signal separating method and circuit - Google Patents

Abstract

The method and circuit using a line correlativity in a composite video signal includes the steps of: performing 1H comb-filtering for more than two signals according to the difference of at least three serial line signals, operating more than two 1H comb-filtered signals to perform 2H comb filtering; comparing detection signals generated according to the line correlativity of the luminance signal in more than two 1H comb-filtered signals and detection signals generated according to the line correlativity of the chrominance signal in the 1H comb-filtered signals with reference signals, and generating coefficient signals; and selecting the 1H comb-filtered signals or the 2H comb-filtered signals according to the coefficient signals and outputting a comb-filtered chrominance signal, thereby efficiently separating a chrominance signal.

Description

Color Signal Separation Method and Circuit Using Line Correlation in Composite Video Signal

1A is a frequency spectrum state diagram showing the bandwidth of a luminance signal used in an NTSC broadcasting system.

Figure 1b is a frequency spectrum state diagram showing the bandwidth of the color signal used in the NTSC broadcasting system.

1C is a distribution state diagram of a frequency spectrum of a composite video signal used in an NTSC broadcasting system.

2 is a circuit diagram of a conventional adaptive comb filter.

3 is a circuit diagram of an adaptive comb filter using a reference signal in the related art.

4 is an implementation circuit diagram of a color signal separation circuit according to the present invention.

5 is an implementation circuit diagram of the coefficient generator according to the present invention.

* Explanation of symbols for main parts of the drawings

1,2,24,25,51,52,53,54: 1H delay part

3,4,11,12,21,22,23,31,32,55,56,59,62,63: adder

5,6,13,14,26,27,28,33,34,57,58,61,64,65: amplifier

7,8,9,35,36,71,72: Low pass filter 10,50,100: Color separation filter

15,16,37,38,68,69,73,74: Absolute value converter

17,39.81: coefficient generator 20,60,200: correlation detection circuit

30: Mixer 40,66,67,80,400: Band Pass Filter

220: luminance signal correlation detector 210: color signal correlation detector

CP1, CP2, CP3... Comparator AD1, AD2, AD3, AND4

OR1, OR2... : Oagate X, Y, Z: Norwood

VRF1: first reference signal VRF2: second reference signal

The present invention relates to a color signal separation method of a composite video signal and a circuit thereof for detecting a correlation between lines of a composite video signal in a system such as a television or a video tape recorder to separate color signals more effectively.

In a system such as a television or a video tape recorder, the luminance signal and the color signal included in the composite video signal have the same relationship with the first degree.

FIG. 1A shows a band of a luminance signal used in an NTSC broadcasting system, and FIG. 1B shows a band of a color signal used in an NTSC broadcasting system. FIG. 1c shows the distribution of the frequency spectrum of the composite video signal used in the NTSC broadcasting system. It can be seen that the luminance signal and the color signal are included in the same frequency band.

In order to separate the luminance signal and the color signal from the composite video signal, the luminance signal is taken using a low pass filter and the color signal is taken using the band pass filter. Since the high frequency component of the luminance signal is included in the cross color, there is a problem in that cross color interference occurs.

In order to solve this problem, a comb filter that can more clearly separate the luminance signal and the color signal has been used.

When the interleaving between the horizontal synchronization signal and the color carrier signal is good, the comb filter can separate the luminance signal and the color signal more clearly and can improve the resolution. The difference between the 1H delayed composite video signal and the input composite video signal is obtained. After dividing by 2, a good color signal can be separated from the composite video signal.

The method of separating color signals using such a comb filter can effectively separate when the signals of two lines (the current line and the immediately above line) are similar to each other (which is said to have a high correlation). The color signal is separated through a pass filter.

2 shows a conventional adaptive comb using the color separation scheme as described above.

The circuit comprises a color separation filter (10) comprising a 1H delay unit (1) (2), an adder (3) (4), an amplifier (5) (6), and a low pass filter (7) (8) (9). ), An adder (11) 12, an amplifier (13), (14), an absolute value converter (15), (16), and a coefficient detecting unit (20) including a coefficient generator (17). The mixer 30 connected between the color separation filter and the correlation detection circuit 20 is configured to separate the color signal through the band pass filter 40.

Therefore, when the composite video signal is input, the delayed signal through the 1H delay unit 1 and the composite video signal are added by the adder 3, and the signal delayed through the 1H delay unit 2 equally receives the 1H delay unit 1. The signal through and the adder 4 are added. Here, each of the adders 3 and 4 performs addition and subtraction.

That is, the adders 3 and 4 on the left and right about the Norwood X obtain the difference between the current line signal and the immediately preceding line signal delayed by 1H through the 1H delay units 1 and 2, and then the amplifier 5 Amplified by 1/2 at 6) and fed to the mixer 30.

This operation is the basic operation of a general comb filter and is the same as the concept of separating the color signal by doubling the current line signal from the current 1H delayed line signal.

In this case, the 1H delay is a delay by the horizontal period. In addition, the correlation detecting circuit 20 is provided with input and output signals of the 1H delay units 1 and 2, respectively, to the low pass filters 7, 8, 9 so that only the luminance component of the composite video signal is obtained. It passes through and inputs to the adders 11 and 12, respectively.

That is, in the left and right adders 11 and 12 centered on the Norwood Y, the signal difference between the luminance signal of the current line and the immediately preceding line is obtained and then amplified by a factor of 1/2 in the amplifiers 13 and 14. This value is input to the absolute value converting section 15 (16).

The absolute value converted by the absolute value converter 15 and 16 is inputted to the coefficient generator 17, and the two line signals are correlated with each other among the three line signals in the currently input composite video signal. By checking whether there is a relationship, one of two input signals input to the mixer 30 connected to the rear stage is selected.

The mixer 30 receives the control signal from the coefficient generator 17, selects a comb-filtered signal from two line signals having a large correlation among the two input signals, and outputs a color signal through the band pass filter 40.

The mixer 30 is described to select one of the two input signals, but both input signals may be input and the ratio of the input signals may be adjusted according to the calculated value of the coefficient generator 17.

In the conventional adaptive comb filter, cross color, dot crawl, and the like due to the vertical transition of the image appearing on the screen can be reduced. Even when large, since 1H comb filtering should be performed on either side of the center X, cross color and dot crawl may occur.

In order to solve this problem, the comb filter of FIG. 3 is used to perform 2H comb filtering when all three line signals in the composite video signal have high correlation.

3 shows an adaptive comb filter using a reference signal.

This circuit comprises a color separation filter 50 comprising adders 21, 22, 23, 1H delay units 234 25, amplifiers 26, 27, 28, and adders 31, 32. ), A correlation detecting circuit 60 including an amplifier 33, 34, a low pass filter 35, 36, an absolute value converter 37, 38, a coefficient generator 39, The selector 70 is connected between the color separation filter 50 and the coefficient generator 39, and the band pass filter 80 is connected to the rear end of the selector 70.

Here, the coefficient generator 39 generates coefficients by comparing with the reference signal VRF. The reference signal VRF is a signal set by a microcomputer or a user and is a reference signal that can be compared according to a correlation of luminance signals. .

The basic operation in this circuit is the same as in the second diagram.

That is, the line signals applied through the 1H delay units 24 and 25 are sequentially delayed so that the three line signals are input and the difference between the line signals applied to the adder 21 on the left side with respect to the norm X is The 1H com-filter is amplified by 1/2 times in the amplifier 26, and the difference of the line signal applied to the adder 22 on the right is also 1H com-filtered and amplified by 1/2 in the amplifier 28.

When the 1H comb filtered left and right status signals are detected by the adder 23, the Norm Z can obtain a 2H comb filtered signal, and in this case, the amplifier 27 is amplified by 1/4 times.

Eventually, when three times the line signal is applied, the comb filtering of the first and second lines, the comb filtering of the second and third lines, and the comb filtering of the first, second and third lines (this is 2H com-filtered Select signals according to the correlation between the lines in the selector 70.

Therefore, when the correlation detecting circuit 60 is viewed from the center of the Norwood Y, each of the 1H com-filtered signals in the adders 31 and 32 is amplified by 1/2 times and the low pass filters 35 and 36 are respectively amplified. The luminance signal is detected and the absolute value converted value is input to the coefficient generator 39.

The coefficient generator 39 controls the selector 70 by calculating a correlation between the lines by calculating the absolute value converted from the reference signal VRF.

For example, if the 1st line and the 2nd line have a high correlation, a 1H com-filtered signal is accepted at the terminal p1, and if the 2nd line and the 3rd line have a high correlation, 1H is received at the terminal p3. Accept the filtered signal.

In addition, the coefficient generator 39 compares the values according to the reference signal VRF and the luminance signal to control the selector 70 when all three lines are correlated to control the selector 70 to the first and second terminals p2. The 3H line filtered signal is received.

The output of the selector 70 outputs a color signal included in the composite video signal through the band pass filter 80.

In this way, the separation of color signals can be achieved only when there is a vertical transition of color signals when there is a vertical transition of luminance signals, and when there is no vertical transition of color signals when there is no vertical transition of luminance signals. However, in the case where there is no vertical transition of the luminance signal, when there is a vertical transition of the color signal, good color separation characteristics cannot be expected.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to detect the vertical correlation of the luminance signal and the vertical correlation of the color signal and to separate the color signals included in the composite image signal. An object of the present invention is to provide a color signal separation method using a correlation.

Another object of the present invention is to provide a color signal separation circuit using a preferred line-to-line correlation that can be implemented by the color signal separation method described above.

In order to achieve the above object, a feature of the present invention is to obtain a difference between a 1H delayed line signal and a next applied line signal, and to perform a 1H comb filtering by doubling the 1H delayed line signal to separate the color signal from the composite video signal. Perform 2H comb filtering by performing at least two 1H comb filters, respectively, according to the difference of at least three consecutive line signals, and calculating two or more 1H comb filtered signals; The detection signals generated according to the correlation between the lines of the luminance signals in the two or more 1H comb filtered signals, and the detection signals generated according to the line correlation of the color signals in the two or more 1H comb filtered signals. To generate a count signal; A color signal separation method using a correlation between lines in a composite image signal in which two or more 1H comb filtered signals and 2H comb filtered signals are output according to the value of the count signal to output comb filtered color signals.

Another feature is a 1H delay unit for delaying a line signal by 1H, an adder for obtaining a difference between a 1H delay signal and a line signal applied next, an amplifier for halving the difference between line signals, and an amplifier. A comb filter in which color signals are separated from a composite video signal by 1H comb filtering, comprising: a first filter means for generating at least two 1H comb filtered outputs, and at least two 1H comb filters output from the first filter means; A color separation filter comprising: a second filter means for generating a 2H comb filtered output at the output; A correlation between the luminance signal correlation detector for detecting correlation in the two or more 1H comb filtered outputs output from the first filter means, and the correlation in the two or more 2H comb filtered outputs output from the first filter means A correlation between a color signal correlation detector for detecting, a coefficient generator for generating an output calculated by comparing the detection signals of the luminance signal correlation detector and the color signal correlation detector with at least one reference signal; A section connected between the color separation filter and the coefficient generator to selectively output a 1H comb filtered color signal and a 2H comb filtered color signal; The color signal separation circuit using the correlation between the lines in the composite video signal consisting of.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

4 shows an implementation circuit diagram of the color signal separation circuit according to the present invention.

The color signal separation circuit includes a color separation filter 100 for outputting a comb-filtered color signal from the composite video signal V, and a correlation detection circuit for detecting a correlation between lines from the composite video signal V; 200, the selector 300 is connected between the color separation filter 100 and the correlation detection circuit 200 to output a color signal through the band pass filter 400 at the rear stage.

The color separation filter 100 includes four 1H delay parts 51-54, and the difference signal through the left and right adders 55 and 56 centered on the norm X is an amplifier ( 57) and 58 so that the 1H com-filtered color signals are output.

In addition, the outputs of the respective amplifiers 57 and 58 are configured to be calculated 1/2 times in the amplifier 61 through the adder 59 so that the 2H com-filtered color signal is input to the terminal p2 of the selector 300. Configure.

The line correlation detection circuit 200 outputs the luminance signal correlation detection unit 220, the color signal correlation detection unit 210, the luminance signal correlation detection unit 220, and the color signal correlation detection unit 210. It consists of a coefficient generator 81 is applied.

The luminance signal correlation detector 220 includes a low pass filter 71 and 72 to which an output of the amplifiers 57 and 58 of the color separation filter 100 is applied, and the low pass filter 71 and 72. The absolute value conversion unit 73 or 74 converts the output of the power to a constant level.

The color signal correlation detector 210 includes an adder 62 and 63 for adding a difference between input and output signals of the delay elements 51 to 54 of the color separation filter 100, and the adder 62 and 63. Amplifiers 64 and 65 for amplifying the output 1/2 times, bandpass filters 66 and 67 to which the outputs of the amplifiers 64 and 65 are supplied, and the bandpass filters 66 and 67; And an absolute value converting section 68 (69) for converting the output of the?) To a constant level.

The coefficient generator 81 receives the first reference signal VRF1 and the second reference signal VRF2 and detects correlation signals S1-S4 of the luminance signal correlation detector 220 and the color signal correlation detector 210. To compare).

When the composite video signal V is applied to the circuit of the present invention configured as described above, a signal in which the composite video signal V is delayed by one line from the 1H delay unit 51 is transmitted through the VH and 1H delay units 51 and 52. The signal delayed by two lines is V2H, the signal delayed by three lines through the 1H delay units 51, 52, and 53. The signal delayed by three lines is V3H, and delayed signals are delayed by four lines through the 51H, 51, 52, 53 and 54 delayed. Becomes

At this time, the overall operation of the circuit is V2H delayed by two lines at the center point of the norm X. In the adder 55, a difference between the V2H and VH signals is generated, and this line signal is a signal doubling from the amplifier 57, and a 1H com-filtered signal is applied to the selector 300. If the composite video signal delayed by 1H is set to VH = EY1 + EC1,

EY1: magnitude of 1H delayed luminance signal

EY2: magnitude of 2H delayed luminance signal

EC1: magnitude of 1H delayed color signal

EC2: 2H delayed color signal

V2H-VH = (EY2-EY1) + (EC1 + EC2).

When the correlation between VH and V2H is large, EY1 = EY2 and EC1 = EC2 can be assumed, so that the color signal separated from the composite video signal is V2H-VH / 2 = EC1 = EC2 at the terminal p1 of the selector 300. Is approved. The adder 56 obtains the signal difference of V3H from V2H, and then the 1H com-filtered signal, which is 1/2 times from the amplifier 58, is applied to the terminal p3 of the selector 300 by the same method as described above.

The 1H com-filtered signals through the amplifiers 57 and 58 are added by the adder 59 so that the signal 1/2 times that of the amplifier 61 is applied to the terminal p2 of the selector 300. This state signal becomes a 2H com-filtered signal. The selector 300 detects a correlation between the luminance signal between V2H and the front line VH and V2H and the back line V3H in order to select an input signal applied to the terminals p1, p2 and p3. .

In the luminance signal correlation detector 220 of the correlation detector 200, the 1H com-filtered signals through the amplifiers 57 and 58 are low-passed through the low pass filters 71 and 72, respectively. (Transition) is detected and the state signals S1 and S2 through the absolute value converting units 73 and 74 are input to the coefficient generator 81.

In addition, in order to detect the vertical transition of the color signal, the color signal correlation detecting unit 210 of the correlation detecting circuit 200 includes the adder 62, V2H and V on the left axis, and the adder on the right side with respect to the center point of the norm V. (63) finds the difference between V2H and V4H, and the absolute value after detecting the vertical transition of the color signal through the bandpass filters 66 and 67 for the signals amplified 1/2 times in the amplifiers 64 and 65, respectively. After the conversion, the state signals S3 and S4 through 68 and 69 are input to the coefficient generator 81.

The coefficient generator 81 compares the state signals S1-S4 of the luminance signal correlation detector 220 and the color signal correlation detector 210 with the first reference signal VRF1 and the second reference signal VRF2. The color signals input to the terminals p1-p3 of the selector 300 are selected to separate the color signals included in the composite image signal through the band pass filter 400.

In such a circuit, the color signal included in the composite video signal is separated by detecting the vertical correlation of the luminance signal and the vertical correlation of the color signal, thereby obtaining a more accurate color signal.

Specific implementation circuit diagram of the coefficient generator 81 is the same as the fifth. The circuit includes a comparator (CP1-CP3) for comparing the correlation detection signal (S1) (S2) of the first reference signal (VRF1) and the luminance signal correlation detector 220, the second reference signal (VRF2) and the color signal Comparator (CP4-CP6) for comparing the correlation detection signal of the correlation detector 210, OA gate (OR1) for detecting the output state of the comparator (CP2) (CP3), and the comparator (CP5) (CP6) OA gate for detecting the output state of the control panel, the output of the comparator (CP1) (CP4) and the output of the oragate (OR1) (OR2) logically determines the binary data (D0) (D1) And a logic processing unit CPX for outputting a signal. The logic processing unit CPX includes an oragate OR3 for detecting an output state of the AND gates AD1 -AD4 and the AND gates AD1 and AD2, and an output state of the AND gates AD3 and AD4. It consists of an oragate (OR4) for detecting the.

The input side of the AND gates AD1 (AD3) and AD4 includes an inverted input inverter and each of the data D0 (D1) capable of controlling the selector 300 to the output side of the OR gates OR3 and OR4. ) Is output.

Here, the first reference signal VRF1 is a signal preset by a microcomputer or a user and is a reference signal for generating a coefficient according to the correlation of the luminance signal. The detection signal S1 (S2) is more than the first reference signal VRF1. If both are large or at least one is large, there is a vertical transition of luminance. Therefore, the signals of the detection signals S1 and S2 are compared.

That is, at this time, the output of the OR gate OR1 is in the state of logic "1", and the output of the AND gate AD4 AD2 is determined by the output of the comparator CP1.

In the case of 1S> S2, the comparator CP1 is in a state of logic "1", the AND gate AD4 is in logic "0", and the output of the AND gate AD2 is in a logic "1" state. On the contrary, when S1 < S2, the output of the comparator CP1 becomes logic " 0 ", so that the output of the AND gate AD4 is logic " 1 ", and the output of the AND gate AD2 is logical " 0 ". .

At this time, since the output of the OR gate OR1 is in the state of logic "1", the output of the AND gates AD1 and AD3 becomes logic "0".

Therefore, the output data D0 and D1 have a relationship as shown in the following table.

As a result, when there is a vertical change in the luminance signal, 1H comb filtering is performed like a conventional adaptive comb filter. The second reference signal VRF2 used here is a reference signal for generating a coefficient according to the correlation between the color signals as a signal preset by a microcomputer or a user.

Contrary to the above, when the detection signals S1 and S2 are smaller than the first reference signal VRF1, since the vertical transition of luminance does not exist, the outputs of the comparators CP3 and CP2 are respectively represented by logic "0". It becomes a state.

Therefore, the output of the OR gate OR1 becomes a logic "0", and the output of the AND gates AD2 and AD4 becomes a logic "0" regardless of the output of the comparator CP1.

At this time, when all of the color signal detection signals S3 and S4 are smaller than the second reference signal VRF2, there is no transition of the color signals, and the outputs of the comparators CP5 and CP6 are logic " 0 " The output of OR2) is logical "0".

As a result, the AND gates AD1 and AD3 become logic " 0 " regardless of other signal lines, so that the data D0 and D1 maintain the state of all logic " 0 " If not, the selector 300 selects the 2H com-filtered signal input to the terminal P2.

When the luminance detection signals S1 and S2 are both smaller than the first reference signal VRF1, there is no vertical transition of the luminance signals. As described above, the output of the AND gates AD2 and AD4 is always logic " The state of 0 "is maintained. At this time, when the color signal detection signals S3 and S4 are both greater than or larger than the second reference signal VREF2, there is a transition of the color signals. The output of the AND gate AD1 AD3 is determined by the output of the comparator CP4.

That is, when S3> S4, the output of the comparator CP4 is logic "1", the AND gate AD1 is logic "1", and the AND gate AD3 is logic "0", and when S3 <S4, the comparator The output of CP4 is a logic "0", and the AND gate AD1 is a logic "0", and the AND gate AD3 is a logic "1", and is operated as shown in the following table.

As a result, when there is no vertical transition of the luminance signal and there is a vertical transition of the color signal, 1H comb filtering is performed as shown in the above table to separate the color signal.

As described above, the present invention performs 2H com-filtering when all three lines have a high correlation when separating color signals included in a composite image signal, and according to the correlation when all three lines do not have high correlation. The 1H comb filtering is adaptively performed. Especially, when detecting the correlation, the color signal can be separated more effectively by detecting the transition in the vertical direction of the color signal between lines together with the transition in the vertical direction of the luminance signal between lines. There is.

In addition, when the color signal is separated using the inter-correlation of the composite video signal, the same effect as described above can be obtained even when the weight is separated by the correlation between the luminance signal and the correlation between the color signals.

Claims (10)

A method of separating a color signal from a composite video signal by performing 1H comb filtering by halving a difference between a 1H delayed line signal and a next applied line signal, wherein the color signal is separated from at least three consecutive line signals. Perform 2H comb filtering by performing at least two 1H comb filters and calculating at least two 1H comb filtered signals; The detection signal generated according to the correlation between the lines of the luminance signal in the two or more 1H comb filtered signal, and the detection signals generated according to the correlation between the lines of the color signal in the two or more 1H comb filtered signal. To be counted so as to generate a counting signal; A color signal separation method using a correlation between lines in a composite image signal in which at least two 1H comb filtered signals and 2H comb filtered signals are output according to the value of the count signal, and the comb filtered color signals are output. The color signal separation method according to claim 1, wherein the inter-line correlation in the composite video signal is detected using the phase characteristic of the color subcarrier between lines when detecting the inter-line correlation of the color signal in the composite video signal. The method of claim 1, wherein when detecting the correlation between lines in the composite video signal, the 1H comb filtered color signal and the 2H comb filtered by the coefficient signal generated according to the correlation between the lines of the luminance signal and the correlation between the lines of the color signal. A color signal separation method using correlation between lines in a composite video signal in which weights are assigned to color signals to output color signals proportionally. A 1H delay unit for delaying the line signal by 1H, an adder for obtaining the difference between the 1H delay signal and the next line signal applied, an amplifier for halving the difference between the line signals, and a 1H comb filter. A comb filter in which a color signal is separated from a composite video signal, the comb filter comprising: first filter means for generating at least two 1H comb filtered outputs; A second filter means for generating a filtered output, a color separation filter comprising a luminance signal correlation detector for detecting a correlation in at least two 1H com-filtered outputs output from the first filter means; A color signal correlation detector for detecting correlation in two or more 2H comb filtered outputs output from the first filter means, the luminance signal correlation detector and a color signal correlation A correlation generator for generating a calculated output by comparing the detection signals of the detector with one or more reference signals; A selector connected between the color separation filter and the coefficient generator to selectively output a 1H comb filtered color signal and a 2H comb filtered color signal; Color signal separation circuit using the correlation between lines in the composite video signal consisting of. 5. The apparatus of claim 4, wherein the first filter means of the color separation filter comprises: a plurality of 1H delay units sequentially delayed by a horizontal period, adders connected between the 1H delay units to obtain a difference in each line signal; And a color signal separation circuit using the correlation between lines in a composite video signal including amplifiers halving the output of the adder. 5. The apparatus of claim 4, wherein the second filter means of the color separation filter comprises: an adder for obtaining a difference of outputs of the amplifiers to be amplified by one and a half times in the first filter means; Color signal separation circuit using the correlation between lines in a composite video signal consisting of, and. 5. The apparatus of claim 4, wherein the luminance signal correlation detector comprises at least one low pass filter to which an output of an amplifier to amplify 1/2 times in the first filter means is applied, and a value calculated by being connected to a rear end of the low pass filter. Color signal separation circuit using the correlation between lines in the composite image signal consisting of one or more absolute value converting unit for outputting. 5. The color signal correlation detecting unit according to claim 4, wherein the color signal correlation detecting unit comprises: at least one adder for obtaining a difference in output of the 1H delay unit in the first filter means, at least one amplifier for amplifying the output of the adder 1/2 times, and the output of the amplifier. At least one bandpass filter having an input signal, at least one absolute value converting unit connected to a rear end of the bandpass filter to convert to a constant level value, and a color signal separation circuit using the correlation between lines in a composite video signal consisting of . The apparatus of claim 4, wherein the coefficient generator comprises: first reference signal comparators for comparing correlations between the first reference signal and the luminance signal correlation detector; Second reference signal comparators for comparing correlations of a second reference signal and a color signal correlation detector, at least one gate sensing an output state of the first reference signal comparators and the second reference signal comparators, and the first reference signal comparator; And a logic processor configured to output binary data by logically comparing the outputs of the second reference signal comparators with the outputs of the one or more gates, and using the correlation between lines in the composite image signal. The method of claim 9, wherein the first reference signal and the second reference signal are signals preset by a microcomputer or a user, wherein the first reference signal is a reference of a luminance signal, and the second reference signal is a reference signal of a color signal. Color signal separation circuit using the correlation between lines in the composite video signal.